I HAVE A PROBLEM WITH MY CENTRAL HEAT ITS ELECTRONIC, WHEN YOU SET THE THERMOSTAT TO ABOUT 70 THE IGNITOR TRYS TO COME ON BUT GOES OUT. SO YOU HAVE TO TURN IT BACK OFF UNTIL UNIT STOPS THEN CRANK IT UP TO ABOUT 80 THEN SOMETIMES IT WILL WORK.I HAVE A CODE THAT SAYS OPEN LIMIT.REPRESENTED BY 4 FLASHES.COULD IT BE THE IGNIGHTER,ANY HELP WOULD BE APRECIATED. THANKS BJ